• O'Briens Wines & Beer
• OASIS Group
• OCC Computer Personnel
• OCS Ireland
• Office Buddies
• Office Talent
• Oliver James
• Oliver St. John Gogarty
• Optimize Recruitment
• Oradeo
• Orange Recruitment
• Orchard Care Group
• Oriel House Hotel
• Orpea Residences Ireland
• Orwell Healthcare
• Osborne Recruitment
• Osprey Hotel
• Oxfam Ireland
• Oxigen Environmental